6-way drive unit



J- PICKLES ETAL April 19, 1966 6-WAY DRIVE UNIT Filed June 12, 1963 6 Sheets-Sheet 1 INVENTORJ JOSEPH 1 /6/1256 A ril 19, 1966 J. PICKLES ETAL 3,246,540

S-WAYDRIVE UNIT Filed June 12, 1963 6 Sheets-Sheet 2 led /3Z 147' 7' ORNfYS April 19, 1966 J. PICKLES ETAL 6WAY DRIVE UNIT 6 Sheets-Sheet 4 Filed June 12, 1963 INVENTORS Josspw P/CA'Z 5s EAMORf 4. 2/5512;

April 19, 1966 J. PICKLES ETAL G-WAYDRIVE UNIT 6 Sheets-Sheet 5 Filed June 12, 1963 4% s s 4 r mm? ,M W ZAZ P WHH A P my? April 19, 1966 PICKLES ETAL 6-WAY.DRIVE UNIT 6 Sheets-Sheet 6 Filed June 12, 1963 m :5 5 R f E N m Mk .k wmz W m 4 A Z. WM? 0M0 5.2M

United States Patent 3,246,540 6-WAY DRHVE UNIT Joseph Pickles, Dearhorn, and Elmore L. Zibbell, Redford, Mich, assignors to Ferro Manufacturing Corporation, a corporation of Michigan Filed June 12, 1963, Ser. No. 287,244 Claims. (Cl. 74-665) The present invention relates to adjustable beds and more particularly to an adjustable bed of the hospital type which is power driven to various positions at the control of the occupant. The present invention is capable of imparting multiple adjustments to the bed and employs a single reversible motor in conjunction with selectively operable control means for effecting the desired adjustments.

Beds of the hospital type have been adjustable in height and to various tilted positions by manual means as well as by power operated equipment. Manual operation requires some one other than the patient or occupant of the bed and therefore manual adjustments can only occur when such a person is present. The degree of tilt and .raising and lowering of the platform of the bed was limited and only a minimum amount and number of manual adjustments were made. With the power operated type of hospital bed illustrated in the prior art, a separate drive motor is provided for each of the adjustments required. In addition, each of the drive motors required separate control mechanisms which made the entire drive assembly of the hospital bed cumbersome, space consuming and expensive.

It is an object of the present invention to overcome the disadvantages associated with manual and power operated hospital beds illustrated in the prior art by providing a single motor multiple drive unit having control means for effecting selective actuation of a plurality of in dependent drive mechanisms to effect the raising and lowering of the head of the bed section, raising and lowering of the knee section of the bed, and the raising and lowering of the frame of the bed with respect to the legs.

Another object of the present invention is to provide a hospital bed of the aforementioned type comprising a single motor multiple drive unit adapted to effect simultaneous synchronous selective actuation of the head and knee sections of the bed.

A further object of the present invention is to provide a multiple way bed adjustment mechanism comprising a single reversible motor, a plurality of gears in mesh with each other, drive means including a control torque slip clutch between the motor and one of the gears, and selectively operable clutch means for clutching each of the gears independently to a shaft on which it is mounted.

A still further object of the present invention is to provide a multiple bed adjustment mechanism comprising a plurality of pinions, a rack associated with each pinion, and linkage mechanism operatively connected between the racks and parts of the bed to effect selective bed adjustments.

Another object of the present invention is to provide a solenoid for each of the selectively operable clutch means, and manual shift means operatively connected to certain ones of the solenoid operated clutch means for operating same to effect disengagement thereof with the corresponding gear in the event of power failure.

Still another object of the present invention is to provide a novel control torque slip clutch which is adapted to be coupled between the reversible drive motor and one of the gears of the drive unit.

A further object of the present invention is to provide a bed of the aforementioned type wherein the drive unit therefore is provided with a housing through which the racks extend, and a pair of stop abutment means are provided on each of the racks at the outer end portions thereof engageable with opposite sides of the housing for limiting the movement of the corresponding rack in op-- posite directions.

A still further object of the present invention is to provide an adjustable bed of the aforementioned type wherein each of the stop abutment means is in the form of a resilient element which yields when it strikes the housing.

A further object of the present invention is to provide a hospital bed of the aforementioned type which is simple in construction, positive in operation and economical to manufacture.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating preferred embodiments of the invention, wherein:

FIGURE 1 is a diagrammatic view of the bed illustrating the rack operated cable and pulley system forming a part of the present invention.

FIGURE 2 is a fragmentary plan view of the power operated bed, with certain parts removed in order to illustrate the drive connections between the movable racks and parts of the bed.

FIGURE 3 is a side elevation of the bed.

FIGURE 4 is a view similar to FIGURE 3 but larger in size and with certain parts removed so as to more adequately illustrate certain features of the present invention.

FIGURE 5 is a plan view of the drive unit, with parts broken away and in section.

FIGURE 6 is a sectional view through the drive unit taken substantially on line 66 of FIGURE 5.

FIGURE 7 is a sectional view through the drive unit taken substantially on line 7-7 o-f FIGURE 5.

FIGURE 8 is an end view of the selectively operable drive unit with the cover removed.

FIGURE 9 is a side view of the rack operated cable support taken on line 99 of FIGURE 4.

FIGURE 10 is a fragmentary perspective View of a rack illustrating a resiliently mounted stop abutment thereon.

FIGURE 11 is a view of the manually operable shift mechanism taken substantially on line 1111 of FIG- URE 5.

FIGURE 12 is a fragmentary sectional view of the control torque slip clutch.

FIGURE 13 is an elevational view of the control torque slip clutch taken on line 1313 of FIGURE 12 and reduced in size.

Referring now in detail to the drawings, a bed of the hospital type is illustrated in FIGURE 1 and is designated by the numeral 10. The bed 10 comprises a horizontally extending rectangular frame 12 which includes end rails 14 and 16 structurally interconnected in bed-forming relationship by side rails 18 and 20. The frame12 includes various structural braces 19 and 21 which make the frame 12 more rigid. The various rails and braces forming the frame 12 may be made from structural steel angles. It should be understood that other shapes of rails and braces may be utilized.

Substantially rectangular guide openings 22 are provided near the ends of the side rails 18 and 20 adjacent the end rails 14 and 16. The guide openings 22 are adapted to receive the telescopic and adjustable legs 24. The legs 24 are provided with casters 26 which are adapted to roll or move on the floor as is conventional in the art. The bed 10 has head and foot end frames 28 and 30 which are interconnected to the sides 31 of the bed 10 and arranged substantially perpendicular to the frame 12 as best illustrated in FIGURE 1.

Secured to and projecting upwardly from the side rails 18 and 20 are side plates 34 and 36, respectively. The bed 10 includes a body supporting adjustable platform 38 formed of structural angles, channels, or the like as best illustrated in FIGURE 3. The bed springs and the mattress, not illustrated, are carried by the platform 38 as is Well known in the art. The platform 38 includes an intermediate bed section 40, a head section 42, and a knee section 44. The inner end of the head section 42 has the longitudinally extending side members thereof pivotally secured to the opposite side plates 34 and 36 by means of a pair of pivot pins 46. The longitudinally extending side members of the knee section 44 are pivotally connected to the side plates 34 and 36 by means of a pair of pivot pins 48.

The two longitudinally extending side members of the head section 42 are provided with downwardly extending flanges Strand 52 while the corresponding side members of the knee section 44 are provided with downwardly extending flanges 54 and 56. The lower portions of the flanges 50' and 52 carry a transversely extending elongated pivot element 58 which is arranged below and substantially parallel to the axes of the pivot pins 46. The lower portions of the flanges 54 and 56 carry a transversely extending elongated pivot element 60 which is arranged below and substantially parallel to the axes of the pivot pins 48. The distance between the axes of the pivot pins d6 and 48 is approximately equal to the distance between the elongated pivot elements 58 and 60. The opposite ends of the elements 58 and 66 are suitably anchored in their respective flanges whereby rotation of the elements 58 and 66 produces corresponding rotation of the head section 42 and knee section 44, respectively.

A pair of actuating arms 64 are secured on one end to the elongated element for rotating the head section 42.

The other end of the arms 64 are connected to the head rack 66 by means of a pivot pin 68. A pair of actuating arms 79 are secured on one end to the elongated element 60 for rotating the knee section 44 and on the other end the arms 70 are connected to the knee rack 72 by means of a pivot pin '74.

The head section 42 includes a pair of downwardly extending stop elements 80 and the knee section 44 includes like stop elements 82. All the stop elements 80 and 82 are engageable with the frame 12 to support and maintain the platform 38 in a substantially horizontal position when no power is applied thereto.

The knee section 44 is divided into two parts including the inner part 8 pivotally connected to the bed section by pivot pins 48 and an outer part 86 for supporting the legs of the body. The inner end of the outer part 86 is pivotally connected to the inner part 84 by means of a pair of pivot pins 88. Each of the pivot pins 88 also supports a downwardly extending swinging arm 90 which is provided with a roller 92 on the lower end thereof. The roller 92 is engageable with an inclined track 94 carried by the frame 12. The swinging arm 90 includes a plurality of teeth 96 selectively engageable with a pawl 98 pivotally carried by the side rail of the outer part 86. When the knee section 44 is raised in a manner to be subsequently described the leg part 86 jack knifes as the rollers 92 provided on the swinging arms 91 move up the inclined tracks 94. When the knee section 44 is in the requiste adjusted position the pawls 98 engage teeth 96 to maintain the leg part 86 in adjusted position with respect to the inner part 84.

7 Means are provided for raising and lowering the, frame 12 with respect to the legs 24 and includes a rack operated.

cable-pulley system for effecting such movement. Each of the legs 24 is provided adjacent its upper end with a tab or lug 106) as best illustrated in FiGURE 1. Each leg 24 is provided'with a corresponding pulley 102 directly below the corresponding lug 1% and mounted on the frame 12. A bracket 104 extends inwardly from the end rail 16 and has mounted thereon pulleys 106 and 108.

A third rack 110, located in between the head rack 66 and the knee rack 72, has a cable support bracket 112 fixedly mounted thereon. Cable 114 has one end fastened to the support bracket 112 by lock nuts 113. Cable 114 extends around a pulley 102 and has the other end fastened to the lug 104 on the right head leg. Cable 116 is secured to the support bracket 112 on one end thereof, extends around the pulley 162 and has the other end secured to the lug 1% provided on the left head leg 24.

A third cable 118 is connected on one end to the cable support 112 and extends forwardly therefrom around pulley 106 and then rearwardly to the pulley 162 correspond ing to the right rear leg 24. Cable 118 extends around said pulley 1&2 and is anchored on the outer end to the corresponding lug 100. A fourth cable 120 is connected on one end to the cable support 112 and extends forwardly therefrom around pulley 1% and then rearwardly to the left rear leg 24. Cable 120 extends around the corresponding pulley 162 and is anchored on the outer end to the corresponding lug 160. Movement of the rack 11% moves the cable support 112 whereby the frame 12 is raised or lowered through the various cables 114, 116, 118, and 120, depending on the direction of movement of the rack 111 The multiple drive unit for making the various adjust ments of the bed 19 is designated by the numeral 124 and includes a single drive motor 126. The drive unit 124 includes a main housing 125 which is mounted in between a pair of centrally located longitudinally extending angle braces 13G forming part of the frame 12. The housing 123 is secured to the flanges of the braces by means of bolts 132 as best illustrated in FIGURE 5. The motor 126 is likewise connected to the frame 12 by bolts, by welding or the like.

Mounted in the housing 128 are three shafts 134, 136, and 138 which are arranged substantially parallel to the drive shaft 139 of the motor 126. The shaft 136 is axially aligned with the drive shaft 139 as will be subsequently explained. Each of the shafts 134, 136, and 138 have mounted thereon gears 140, 142, and 144, respectively, which are in meshed engagement as best illustrated in FIGURE 8. The gears are independently mounted on said shafts and are free to rotate with respect thereto. When the motor 126 is energized, the gears 141i, 142 and 144, being in mesh with each other, all rotate freely on their respective shafts. In order to effect selective adjustment of the bed 10, each of the shafts 134, 136 and 138 has clutch mechanism associated therewith and with the related gear. In FIGURE 6, the shaft 136 is shown as having a clutch element or clutch means 146 which is longitudinally slideable thereon between gear 142 and the bushing 148 carried by shaft 136. The gear 142 is fixedly carried by a hub 15%) which is mounted for independent rotation on shaft 136.

Axially aligned with the shaft 136 is the shaft 152 of a control torque slip clutch 154. The slip clutch shaft 152 is axially aligned with and coupled directly to the shaft 139 of the drive motor 126. When the torque of the motor reaches, as an example, 2224 inch-pounds, the friction disks of the clutch 154 grip the opposite plates which are connected to the annular flange 156 provided on the hub 150. Thereafter, the gear 142 is effective to rotate the gears in mesh therewith.

In order to selectively control rotation of each of the shafts, such as the shaft 136, a solenoid indicated generally at 160 is provided which includes conventional windings, not shown, adapted to be energized by electrical con ductors, not shown. The solenoid 160 includes a movable plunger or armature 164 having a fork or lever coupling 1166 mounted on the outer end thereof. The fork 166 is engageable with an annular groove 168 on the periphery of the clutch element or coupling drive 14-5. The fork 166 is biased by a spring 170 away from the gear 142 and hub 15th. It will be understood that when the solenoid 160 is energized to move the armature 164 to the left as viewed in FIGURE 6, the coupling drive 146 engages correspondingly shaped clutch teeth on the hub 150 on which the gear 142 is mounted and hence rotation is imparted to the shaft 136. It will, of course, be appreciated that each of the gears is selectively controlled by a separate solenoid 160, fork 166 and coupling drive 146. The forks 166 provided on shafts 134 and 138 are each provided with a spring 169 which is used for a purpose to be hereinafter described.

Carried by the three shafts 134, 136, and 138 are worms 172, 174, and 176, respectively. The worms 172, 174, and 176 are in mesh respectively with worm gears 17-8, 180 and 182 each mounted for free rotation independently of the others. The worm gears 178, 180 and 182 are connected to or integral with pinions 184, 186 and 188 respectively. The pinions 184, 186 and 188 are engageable respectively with the racks 72, 110, and 66.

The shafts 138 and 134 for the head section 42 and knee section 44, respectively, are each provided with a manual shift mechanism which is effective to manually operate the solenoid controlled coupling 146 in the even-t of power failure of the motor 126 or the solenoids 160. It should be appreciated that after the head section 42 or the knee section 44 is actuated or raised to a tilted or non-horizontal position, the solenoid 160 associated therewith is de-energized so as to return the fork 166 and the coupling 14-6 to the uncoupled position illustrated in the lower left hand corner of FIGURE 5 wherein the coupling 146 is disengaged from the hub 150. In the event of power failure, the manual shift mechanism is effective to re-engage the corresponding coupling 146 with the hub 150. Thereafter, by means of a crank or handle not illustrated, the drive shaft 139 of the motor 126 is rotated so as to drive the corresponding shaft 138 or 134 in the direction required to lower the corresponding head or knee section.

The transmission housing 128 includes a removable end cover 190 which carries a pair of right'angle levers 192, one lever corresponding to each of the shafts 134 and 138. Each lever 192 is mounted in the cover 190 for rotation throughout 180 degrees as best illustrated in FIG- URE 11. Arm 194 of the lever 192 is rotatably carried by the cover 190 and is provided with an undercut or recess 196. The aforesaid spring 169 is anchored on one end to the outer surface of the fork 166 as indicated at 198 in FIGURE 5. The spring 169 is shaped so as to include an outwardly extending portion 199 which is received in the recess 196 provided in the lever 192. The other end portion of the spring 169 extends through a slot 200 provided in the fork 166, with the free end thereof forming a tab 281 which normally engages the back side of the fork 166. Upon power failure, the other arm 202 of the lever 192 :is rotated so as to rotate arm I94 counterclockwise as indicated by arrow A in FIG- URE 5. As a result thereof, the outer surface 204 of the arm 194 engages the spring part 199 and shifts the coupling 146 into engagement with the 'hub 150. If the knee section 44 is to be lowered, the motor 126 is manually driven by means of a crank, not illustrated, which rotates the corresponding shaft 134, worm 172, gear 178,

pinion 184 and the rack 72 in the required direction so as to lower the head section.

The solenoids 160 are each provided with a cover plate 204 as by rivets or the like. The entire cover portion is attached to the transmission housing 128 by screws 206. FIGURE 7 illustrates the front of one solenoid 160 at the left and the rear of another solenoid 160 at the right.

The three racks 66, 110, and 72 extend through the transmission housing 128 and are enclosed therein by means of a rack cover 210 which is attached to the housing 128 by bolts or screws 212. Each rack is'provided on the end portions thereof with a pair of resilient or yieldab'le stop abutments 214 (see FIGURE 10), one abutment 214 on each side of the transmission housing 128. Specifically, each abutment 214 is in the form of a spring plate which is bowed in the direction of the applied load as indicated by arrow B in FIGURE 10. The spring plate 214 is rectangular and is provided with a rectangular opening 216 therein which receives the rectangularly shaped track in substantially tight relationship. The rear surface 217 of the plate 214 adjacent the end of the rack is in engagement with a roll pin 218 which is carried by the rack. The front surface 219 of the plate is engageable with one of the sides 220 of the entire transmission housing as illustrated in FIGURE 5. As an example, when rack 72 is moved to the left as viewed in FIGURE 5, the surface 219 of the spring 214 strikes the housing side 220 and yields or deflects such that the spring plate 214 tends to straighten out. The roll pin 218 prevents the spring plate 214 from moving rearwa-rdly and also absorbs the impact which takes place when the spring plate 214 strikes the transmission housing. It should be understood that each rack is provided with two stop abutments on opposite sides of the transmission housing for limiting the movement of the rack in opposite directions. By controlling the movement of the racks the amount of movement of the various sections of the bed is likewise controlled: I

FIGURES 12 and 13 illustrate the control torque slip clutch 154 mentioned previously in connection with FIG- URE 6. The shaft 152 is mounted in the clutch housing 230 which is attached to the housing 128 by means of bolts 232 illustrated in FIGURE 6.

' The shaft 152 is provided with a flange 234. The inner end of the shaft 152 is threaded for the reception of a nut 236 which cooperates with the flange 234 as will readily appear. The portion 235 of the shaft 152 intermediate flange 234 and nut 236 is provided with a pair of flats 23S.

Mounted on the shaft portion 235 between flange 234 and nut 236 are three cup washers 240 which have an opening therein corresponding to the shape of the shaft portion 235. A pair of clutch discs 242 are interposed between the cup washers 241) and are provided with circular openings therein through which the shaft portion 235 extends. The outer periphery of the two clutch discs 'are each provided with a plurality of recesses or slots 244, as an example six slots each, which are equally spaced apart. Corresponding slots 244 in the discs receive a tab 246 provided on the annular flange 156. In the present embodiment six tabs are provided.

interposed on the shaft portion 235 on opposite sides of each of the clutch discs 242 are friction discs 248. Each friction disc 248 has two friction surfaces, one of which engages a surface on a clutch disc 242 and the other surface engages a surface on a cup washer 240. The friction discs 248 have centrally located circular openings therein.

A pair of spring washers 258 are placed on opposite ends of the shaft-portion 235 with one spring washer 250 engaging the flange 234 and the other spring washer 250 engaging the nut 2 36. It will be appreciated that the various parts are placed on the shaft in the order illustrated in FIGURE 12 prior to placing and tightening the nut 236 on the shaft. After the nut is set to determine the proper torque, the lock washer 252. is utilized to maintain the setting.

The various discs are oiled before assembly. The nut f2136 is first tightened until the spring washers 250 are The nut 236 is then loosened until the breakaway torque reachesapproximately 2628 inch-pounds. Thereafter, the lock washer 252 is secured to fix the setting of the clutch. With such a construction it has been found that the torque after run in is approximately 22-24 inchpounds. 7

Fromthe above description, it is apparent that once the motor 126 is energized, the shaft 152 and cup washers 240 of the friction slip clutch 154 will rotate. The shaft 136, hub 150, friction discs 248 and the clutch discs 242 7 interconnected to the hub connections remain motionless until the requisite running torque has been obtained at which time the friction discs 248 frictionally engage the opposing surfaces on the clutch discs 242 and cup washers 24d and as a result thereof rotate said clutch discs 242, hub 150 and shaft 136. At such time the shafts 152 and 136 rotate together for the purpose of transmitting power from the motor 125 to the transmission.

The various bushings, pins (which connect the hubs to the shafts), seals, set screws, bolts, O-rings, snap-rings, and the like have not been designated or described herein for the purpose of clarity.

The bed It is adapted to be operated by a remote push button control, not shown. The control, which is adapted to be operated by the patient, includes six push buttons. Che push button is for raising the head section 42 and one is for lowering the head section 42. Another set of push buttons is for raising the bed 10 and for lowering the bed 1t) and finally a third set of push buttons is provided for raising the knee section 44 and lowering the knee section 44. With such a push button control the bed 1% may be adjusted to any desired position by the patient. The present construction is designed such that the head section 42 may be raised or tilted about pivot pins 56 approximately 60 degrees from the horizontal while the knee section 44 may be raised or tilted about pivot pins 48 55 degrees from the horizontal.

In operation, when it is required to raise the bed verti cally from the normal horizontal position the appropriate push button corresponding to bed-up is actuated. As a result, the motor 126 is energized and the solenoid 160 corresponding to rack 110 is energized so as to bring the clutch element or coupling 146 into engagement with the corresponding hub 150 as best illustrated in FIGURE 6. Thereafter, the shaft 136 is rotated so as to rotate the worm 174, gear 18%, pinion 186, and the rack 110 in the proper direction. In FIGURE 1, the rack 110 is moved to the right to raise the bed 10 and is moved to the left upon actuation of the bed-down push button to lower the bed through the cable and pulley system described previously.

When it is required to adjust the head section 42 from the normal horizontal position'the push button designated head-up is actuated so as to energize the motor 126 and the corresponding shaft 138, worm 176, gear 182, pinion 188 and finally move the rack 66 to the right as viewed in FIGURE 2. The head section 42 is lowered by actuating the head-down push button. When it is required to raise the knee section 44 the push button designated knee-up is actuated so as to energize the motor 126 and the corresponding shaft 134, worm 172, gear 178, pinion 184 and finally move the rack 72 to the left as viewed in FIGURE 2. Simultaneously upon the tilting of the knee section 44 the leg part 86 is tilted downwardly about pivot. pins 88 as the rollers 92 move upwardly along the inclined track 94 as previously explained. The entire knee section 42 is lowered by actuating the knee-down push button.

It will of course be apparent that selective control of the bed adjustment is effected by reversing the motor 126 for either forward or reverse rotation and selectively controlling engagement of the several clutch elements or couplings 146 so as to transmit rotation in the appropriate direction to the shafts 134, 136 and 138. It will further be observed that the driving connections to the various pinions each include a worm and a worm gear so that upon de-energization of the motor 126 or de-clutching of the drive shaft 139 the bed adjusting mechanism remains locked in an adjusted position.

In the event of power failure the manual shift levers 192 may be operated whereby the knee section 44 and head section 42 may be returned to the horizontal as pre viously explained.

The drawings and the foregoing specification constitute a description of the improved 6-way drive unit in such flange 156 by the tab-slot full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What We claim as our invention is:

1. In combination, a plurality of independently rotatable shafts, a gear rotatably mounted on each of said shafts, a reversible motor, drive means connecting said motor to one of said gears, a separate solenoid actuated clutch selectively coupling each of said gears to the shaft on which it is mounted, and. manually operable means operatively connected to at least one of the solenoid actuated clutches to permit manual operation thereof in the event of power failure.

2. In combination, a plurality of independently rotatable shafts, a gear rotatably mounted on each of said shafts, said gears being in mesh with each other, a reversible motor, drive means including a control torque slip clutch connecting said motor to one of said gears, a separate solenoid actuated clutch selectively coupling each of said gears to the shaft on which it is mounted, and manually operable means operatively connected to at least one of the solenoid actuated clutches to permit manual operation thereof in the event of power failure, said control torque slip clutch permitting said motor to drive one of said gears only after said motor attains a predetermined torque.

3. A drive unit comprising a reversible motor, a plurality of shafts mounted for independent rotation, a gear rotatably mounted on each of said shafts, independently solenoid actuated clutch means for coupling each of said gears to the shaft on which it is mounted, drive means connecting said motor to one of said gears, and manually operable means operatively connected to at least one of the solenoid actuated clutches to permit manual operation thereof in the event of power failure.

4. A drive unit comprising a reversible motor, a plurality of shafts mounted for independent rotation, a gear rotatably mounted on each of said shafts, said gears being in mesh with each other, independently solenoid actuated clutch means for coupling each of said gears to the shaft on which it is mounted, drive means including a control torque slip clutch connecting said motor to one of said gears, and manually operable means operatively connected to at least one of the solenoid actuated clutches to permit manual operation thereof in the event of power failure, said control torque slip clutch permitting said motor to drive one of said gears only after said motor attains a predetermined torque.

5. A drive unit comprising a reversible motor, a plurality of shafts mounted for independent rotation, a gear rotatably mounted on each of said shafts, independently solenoid actuated clutch means for coupling each of said gears to the shaft on which it is mounted, and drive means including a control torque slip clutch connecting said motor to one of said gears, said control torque slip clutch permitting said motor to drive one of said gears only after said motor attains a predetermined torque.

6. A power control system for a bed of the type including a support for a reclining person, said support having independently movable head rest and leg rest por' tions, first elevating means to raise and lower said support, second elevating means to raise and lower said head rest portion, and third elevating means to raise and lower said leg rest portion, said power control system comprising a reversible motor, a housing, three independently rotatable shafts mounted in said housing, a gear rotatably mounted on each of said shafts, selectively energizable solenoid actuated clutches for coupling each of said gears on the shaft on which it is mounted, drive means connecting said motor to one of said gears, a worm on each of said shafts, a Worm gear in mesh With each of said worms, means supporting each of said worm gears in said housing for rotation about its axis, a pinion connected for rotation to each of said worm gears, three racks extending through said housing, each rack in mesh with each pinion, and means mechanically connecting each of said racks with one of said elevating means, the energization of each selectively energizable solenoid actuated clutch being effective to couple the corresponding gear to its shaft and thereafter rotate the corresponding shaft, worm, worm gear, pinion and rack to operate the corresponding elevating means.

7. The power control system defined in claim 6 wherein a pair of stop abutment means are provided on one of said racks at the outer end portions thereof exteriorly of said housing, one of said stop abutment means being engageable with said housing for limiting the movement of said one rack in one direction and the other of said stop abutment means being engageable with another part of said housing for limiting the movement of said one rack in the opposite direction.

8. The power control system defined in claim 7 wherein each of said stop abutment means is in the form of a spring-like element which yields when it strikes said housmg.

9. The power control system defined in claim 8 wherein each spring-like element is bowed in the direction of the applied load whereby upon striking said housing said element deflects and straightens itself.

10. The power control system defined in claim 7 wherein each of said racks is provided with said pair of stop abutment means.

11. The power control system defined in claim 6 wherein said drive means includes a control torque slip clutch which permits said motor to drive one of said gears only after said motor attains a predetermined torque.

12. The power control system defined in claim 6 wherein manually operable means is carried by said housing and is operatively connected to at least one of said solenoid actuated clutches to permit manual operation thereof in the event of power failure.

13. A single motor multiple drive unit comprising a reversible motor, a housing, three independently rotatable shafts mounted in said housing, a gear rotatably mounted on each of said shafts, selectively energizable solenoid actuated clutches for coupling each of said gears on the shaft on which it is mounted, drive means connecting said motor to one of said gears, a worm on each of said shafts, a worm gear in mesh with each of saidworms, means supporting each of said worm gears in said housing for rotation about its axis, a pinion connected for rotation to each of said worm gears, three racks extending through said housing, each rack in mesh with each pinion, the energization of a selected solenoid actuated clutch being effective to couple the corresponding gear to its shaft and thereafter rotate the corresponding shaft, worm, worm gear, pinion and rack, and manually operable means carried by said housing and operatively connected to at least one of said solenoid actuated clutches to permit manual operation thereof in the event of power failure.

14. A single motor multiple drive unit comprising a reversible motor, a housing, three independently rotatable shafts mounted in said housing, a gear rotatably mounted on each of said shafts, selectively energizable solenoid actuated clutches for coupling each of said gears on the shaft on which it is mounted, drive means connecting said motor to one of said gears, a worm on each of said shafts, a worm gear in mesh with each of said worms, means supporting each of said Worm gears in said housing for rotation about its axis, a pinion connected for rotation to each of said worm gears, three racks extending through said housing, each rack in mesh with each pinion, the energization of a selected solenoid actuated clutch being effective to couple the corresponding gear to its shaft and thereafter rotate the corresponding shaft, worm, worm gear, pinion and rack, said drive means including a control torque slip clutch which permits said motor to drive one of said gears only after said motor attains a predetermined torque.

15. A single motor multiple drive unit comprising a reversible motor, a housing, three independently rotatable shafts mounted in said housing, a gear rotatably mounted on each of said shafts, selectively energizable solenoid actuated clutches for coupling each of said gears on the shaft on which it is mounted, drive means connecting said motor to one of said gears, a worm on each of said shafts, a worm gear in mesh With each of said worms, means supporting each of said worm gears in said housing for rotation about its axis, a pinion connected for rotation to each of said worm gears, three racks extending through said housing, each rack in mesh with each pinion, the energization of a selected solenoid actuated clutch 'being effective to couple the corresponding gear to its shaft and thereafter rotate the corresponding shaft, worm, worm gear, pinion and rack, said drive means including a control torque slip clutch which permits said motor to drive one of said gears only after said motor attains a predetermined torque, and manually operable means carried by said housing and operatively connected to at least one of said solenoid actuated clutches to permit manual operation thereof in the event of power failure.

References Cited by the Examiner UNITED STATES PATENTS 2,179,171 11/1939 Boho 74-665 2,755,488 7/1956 Fuhrer 5-69 2,802,219 8/ 1957 Travis 5-64 2,827,641 3/ 1958 Reichert 5-63 2,912,704 11/1959 Burst 5-69 2,913,300 11/1959 Darnell et al 5-68 2,931,242 4/1960 Pickles 74-665 3,012,253 12/1961 Reichert 5-68 3,049,935 8/ 1962 Simmons et a1 74-665 FRANK B. SHERRY, Primary Examiner. 

1. IN COMBINATION, A PLURALITY OF INDEPENDENTLY ROTATABLE SHAFTS, A GEAR ROTATABLY MOUNTED ON EACH OF SAID SHAFTS, A REVERSIBLE MOTOR, DRIVE MEANS CONNECTING SAID MOTOR TO ONE OF SAID GEARS, A SEPARATE SOLENOID ACTUATED CLUTCH SELECTIVELY COUPLING EACH OF SAID GEARS TO THE SHAFT ON WHICH IT IS MOUNTED, AND MANUALLY OPERABLE MEANS OPERATIVELY CONNECTED TO AT LEAST ONE OF THE SOLENOID ACTUATED CLUTCHES TO PERMIT MANUAL OPERATION THEREOF IN THE EVENT OF POWER FAILURE. 